1. Technical Field of the Invention
The present invention relates to a sealing device for sealing a joint constituted by two sealing surfaces facing each other.
The sealing device according to the invention is intended for sealing a joint in which the sealing surfaces are displaceable in parallel with each other. Such a joint can for example be constituted by a joint between two pipe end portions in which the pipe end portions are provided with a socket and a spigot end and the joint is constituted between the substantially cylindrical inner surface of the socket and the substantially cylindrical outer surface of the spigot end introduced into the socket. The sealing device according to the invention comprises a sealing element formed by elastomeric materials of at least two different hardnesses, the sealing element being compressed in the joint while contacting the sealing surfaces.
2. Prior Art
In a sealing device of said kind it is desirable that the sealing device shall prevent or at least counteract displacement of the sealing surfaces from the position in which the sealing surfaces form said joint. In a pipe joint for this purpose it is previously known to use a roller sealing ring having a drop-shaped cross-section, the roller sealing ring having subsequently to the establishment of the pipe joint its smallest dimension positioned transversely to the sealing surfaces in the joint between the sealing surfaces. When making an attempt to displace the sealing surfaces from the position in which the sealing surfaces constitute the joint there is established a resistance because of the fact that the sealing ring rolls against a position in which it has its largest dimensions of the cross-section.
The object of the invention is to provide an improved sealing device of the kind which prevents or obstructs displacement of the sealing surfaces from the position in which the sealing surfaces form the joint.
In order to comply with this object the sealing device according to the invention is characterized by the fact that the sealing element forms two portions of elastomeric material having low hardness, said portions engaging the sealing surfaces, that the elastomeric material having high hardness is positioned between the portions having low hardness and contacting the sealing surfaces and that the elastomeric material having high hardness is adapted at parallel movement of the sealing surfaces from the position for forming the joint to increase its size in a direction transversely in relation to the sealing surfaces.
In a sealing device of this kind the efficiency of the sealing device is improved with regard to the sealing of the joint as well as the capacity of preventing parallel displacement of the sealing surfaces from the position in which the sealing surfaces form the joint. The improved sealing efficiency is provided by the fact that the sealing element contacts and engages the sealing surfaces with elastomeric material having low hardness which provides that the sealing element closely adapts to irregularities of the sealing surface and in spite of such irregularities provide for an efficient sealing. Because of the fact that the elastomeric material having high hardness is used for preventing a parallel displacement of the sealing surfaces from the position forming the joint such displacement is prevented with greater efficiency. In previously known sealing devices one has been referred to provide a compromise between low hardness of the elastomeric material for providing an efficient sealing and a high hardness of the elastomeric material in order to prevent said displacement of the sealing surfaces from the position in which the sealing surfaces define the joint.
The sealing device according to the invention can be designed in different ways. In one embodiment the elastomeric material having high hardness forms two portions which at the displacement of the sealing surfaces from the position for forming the joint are displaced towards each other and by acting on each other are displaced against one sealing surface each. Thereby the portions having high hardness can be adapted to act on each other by cooperation between substantially parallel, concentric, conical surfaces.
In another embodiment of the sealing device according to the invention the elastomeric material having high hardness forms one or several portions which in section have different dimensions in different directions. Thereby, the sealing device is adapted at displacement of the sealing surfaces from the position for forming the joint to change its position from a position in which the elastomeric material portions having high hardness present small dimensions perpendicular to the sealing surfaces into a position in which the portions having high hardness present larger dimensions perpendicular to the sealing surfaces. In this embodiment the elastomeric material having high hardness can in the sealing element form a portion formed as a layer or several portions formed as layers. In the position in which the sealing surfaces form the joint the portions forming the layers take a position in which they are substantially parallel with the sealing surfaces. At an attempt to displace the sealing surfaces from the position in which the surfaces define the joint the portions forming the layers are rotated towards a position in which the layers take a more transverse relationship to the sealing surfaces which prevents or counteracts the displacement of the sealing surfaces from the position in which they form the joint.
In another embodiment of the sealing device according to the invention the sealing surfaces have sections with greater and smaller distances between the sealing surfaces. Thereby, the portion consisting of elastomeric material with great hardness is adapted at the parallel displacement of the sealing surfaces from the position for forming the joint to be displaced from a section having a large distance between the sealing surfaces towards a section having less distance between the sealing surfaces. In this embodiment the sealing element can comprise a portion with a low hardness contacting one of the sealing surfaces and a portion connected therewith and foldable against this. Subsequently to the folding the foldable portion has a portion having low hardness contacting the other sealing surface and a portion with high hardness positioned between the portions having low hardness. The sealing device according to this embodiment is especially well suited to be used in a joint between a socket and a spigot end of two pipe end portions.
In the sealing device according to the invention it is also possible to design the elastomeric material having high hardness as one or several portions which are folded when the sealing surfaces are displaced in parallel to the position for forming the joint. Thereby these foldable portions will take a somewhat folded position in the joint. When the sealing surfaces are displaced in parallel from the position for forming the joint this displacement is counteracted by the fact that the folded portions are displaced towards a raised-up position. In the last-mentioned embodiment the elastomeric material having high hardness can have for example an L-shaped, a U-shaped, an I-shaped or a X-shaped cross section.